.\" $OpenBSD: CMS_get0_RecipientInfos.3,v 1.8 2022/03/31 17:27:16 naddy Exp $
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.Dd $Mdocdate: March 31 2022 $
.Dt CMS_GET0_RECIPIENTINFOS 3
.Os
.Sh NAME
.Nm CMS_get0_RecipientInfos ,
.Nm CMS_RecipientInfo_type ,
.Nm CMS_RecipientInfo_ktri_get0_signer_id ,
.Nm CMS_RecipientInfo_ktri_cert_cmp ,
.Nm CMS_RecipientInfo_set0_pkey ,
.Nm CMS_RecipientInfo_kekri_get0_id ,
.Nm CMS_RecipientInfo_kekri_id_cmp ,
.Nm CMS_RecipientInfo_set0_key ,
.Nm CMS_RecipientInfo_decrypt ,
.Nm CMS_RecipientInfo_encrypt
.Nd CMS EnvelopedData RecipientInfo routines
.Sh SYNOPSIS
.In openssl/cms.h
.Ft STACK_OF(CMS_RecipientInfo) *
.Fo CMS_get0_RecipientInfos
.Fa "CMS_ContentInfo *cms"
.Fc
.Ft int
.Fo CMS_RecipientInfo_type
.Fa "CMS_RecipientInfo *ri"
.Fc
.Ft int
.Fo CMS_RecipientInfo_ktri_get0_signer_id
.Fa "CMS_RecipientInfo *ri"
.Fa "ASN1_OCTET_STRING **keyid"
.Fa "X509_NAME **issuer"
.Fa "ASN1_INTEGER **sno"
.Fc
.Ft int
.Fo CMS_RecipientInfo_ktri_cert_cmp
.Fa "CMS_RecipientInfo *ri"
.Fa "X509 *certificate"
.Fc
.Ft int
.Fo CMS_RecipientInfo_set0_pkey
.Fa "CMS_RecipientInfo *ri"
.Fa "EVP_PKEY *pkey"
.Fc
.Ft int
.Fo CMS_RecipientInfo_kekri_get0_id
.Fa "CMS_RecipientInfo *ri"
.Fa "X509_ALGOR **palg"
.Fa "ASN1_OCTET_STRING **pid"
.Fa "ASN1_GENERALIZEDTIME **pdate"
.Fa "ASN1_OBJECT **potherid"
.Fa "ASN1_TYPE **pothertype"
.Fc
.Ft int
.Fo CMS_RecipientInfo_kekri_id_cmp
.Fa "CMS_RecipientInfo *ri"
.Fa "const unsigned char *id"
.Fa "size_t idlen"
.Fc
.Ft int
.Fo CMS_RecipientInfo_set0_key
.Fa "CMS_RecipientInfo *ri"
.Fa "unsigned char *key"
.Fa "size_t keylen"
.Fc
.Ft int
.Fo CMS_RecipientInfo_decrypt
.Fa "CMS_ContentInfo *cms"
.Fa "CMS_RecipientInfo *ri"
.Fc
.Ft int
.Fo CMS_RecipientInfo_encrypt
.Fa "CMS_ContentInfo *cms"
.Fa "CMS_RecipientInfo *ri"
.Fc
.Sh DESCRIPTION
.Fn CMS_get0_RecipientInfos
returns all the
.Vt RecipientInfo
structures associated with the
.Vt EnvelopedData
structure
.Fa cms .
.Pp
.Fn CMS_RecipientInfo_type
returns the type of
.Fa ri :
.Bl -column CMS_RECIPINFO_TRANS for -compact
.It Dv CMS_RECIPINFO_TRANS Ta for Ta Vt KeyTransRecipientInfo ,
.It Dv CMS_RECIPINFO_AGREE Ta for Ta Vt KeyAgreeRecipientInfo ,
.It Dv CMS_RECIPINFO_KEK   Ta for Ta Vt KEKRecipientInfo ,
.It Dv CMS_RECIPINFO_PASS  Ta for Ta Vt PasswordRecipientinfo , No or
.It Dv CMS_RECIPINFO_OTHER Ta for Ta Vt OtherRecipientInfo .
.El
.Pp
.Fn CMS_RecipientInfo_ktri_get0_signer_id
retrieves the certificate
.Vt RecipientIdentifier
associated with the
.Vt KeyTransRecipientInfo
structure
.Fa ri .
Either the
.Vt SubjectKeyIdentifier
will be set in
.Fa keyid
or both issuer name and serial number in
.Fa issuer
and
.Fa sno .
.Pp
.Fn CMS_RecipientInfo_ktri_cert_cmp
compares the
.Fa certificate
against the
.Vt KeyTransRecipientInfo
structure
.Fa ri .
.Pp
.Fn CMS_RecipientInfo_set0_pkey
associates the private key
.Fa pkey
with the
.Vt KeyTransRecipientInfo
structure
.Fa ri .
.Pp
.Fn CMS_RecipientInfo_kekri_get0_id
retrieves the key information from the
.Vt KEKRecipientInfo
structure
.Fa ri .
Fields are copied out as follows:
.Bl -column keyEncryptionAlgorithm to -compact
.It Fa keyEncryptionAlgorithm Ta to Ta Pf * Fa palg ,
.It Fa keyIdentifier          Ta to Ta Pf * Fa pid ,
.It Fa date                   Ta to Ta Pf * Fa pdate Pq optional ,
.It Fa other.keyAttrId        Ta to Ta Pf * Fa potherid Pq optional ,
.It Fa other.keyAttr          Ta to Ta Pf * Fa pothertype Pq optional .
.El
Where a field is optional and absent,
.Dv NULL
is written to the corresponding parameter.
Parameters the application is not interested in can be set to
.Dv NULL .
.Pp
.Fn CMS_RecipientInfo_kekri_id_cmp
compares the identifier in the
.Fa id
and
.Fa idlen
parameters against the
.Fa keyIdentifier
field of the
.Vt KEKRecipientInfo
structure
.Fa ri .
.Pp
.Fn CMS_RecipientInfo_set0_key
associates the symmetric
.Fa key
of length
.Fa keylen
with the
.Vt KEKRecipientInfo
structure
.Fa ri .
.Pp
.Fn CMS_RecipientInfo_decrypt
attempts to decrypt the
.Vt RecipientInfo
structure
.Fa ri
in
.Fa cms .
A key must have been associated with
.Fa ri
first.
.Pp
.Fn CMS_RecipientInfo_encrypt
attempts to encrypt the
.Vt RecipientInfo
structure
.Fa ri
in
.Fa cms .
A key must have been associated with
.Fa ri
first and the content encryption key must be available,
for example by a previous call to
.Fn CMS_RecipientInfo_decrypt .
.Pp
The main purpose of these functions is to enable an application to
lookup recipient keys using any appropriate technique when the simpler
method of
.Xr CMS_decrypt 3
is not appropriate.
.Pp
In typical usage, an application retrieves all
.Vt CMS_RecipientInfo
structures using
.Fn CMS_get0_RecipientInfos
and checks the type of each using
.Fn CMS_RecipientInfo_type .
Depending on the type, the
.Vt CMS_RecipientInfo
structure can be ignored or its key identifier data retrieved using
an appropriate function.
If the corresponding secret or private key can be obtained by any
appropriate means, it can then be associated with the structure and
.Fn CMS_RecipientInfo_decrypt
called.
If successful,
.Xr CMS_decrypt 3
can be called with a
.Dv NULL
key to decrypt the enveloped content.
.Pp
The function
.Fn CMS_RecipientInfo_encrypt
can be used to add a new recipient to an existing enveloped data
structure.
Typically an application will first decrypt an appropriate
.Vt CMS_RecipientInfo
structure to make the content encrypt key available.
It will then add a new recipient using a function such as
.Xr CMS_add1_recipient_cert 3
and finally encrypt the content encryption key using
.Fn CMS_RecipientInfo_encrypt .
.Sh RETURN VALUES
.Fn CMS_get0_RecipientInfos
returns an internal pointer to all the
.Vt CMS_RecipientInfo
structures, or
.Dv NULL
if an error occurs.
.Pp
.Fn CMS_RecipientInfo_type
returns an integer constant.
.Pp
.Fn CMS_RecipientInfo_ktri_get0_signer_id ,
.Fn CMS_RecipientInfo_set0_pkey ,
.Fn CMS_RecipientInfo_kekri_get0_id ,
.Fn CMS_RecipientInfo_set0_key ,
.Fn CMS_RecipientInfo_decrypt ,
and
.Fn CMS_RecipientInfo_encrypt
return 1 for success or 0 if an error occurs.
.Pp
.Fn CMS_RecipientInfo_ktri_cert_cmp
and
.Fn CMS_RecipientInfo_kekri_id_cmp
return 0 when
.Fa ri
matches or non-zero otherwise.
.Pp
Any error can be obtained from
.Xr ERR_get_error 3 .
.Sh SEE ALSO
.Xr CMS_ContentInfo_new 3 ,
.Xr CMS_decrypt 3
.Sh STANDARDS
RFC 5652 Cryptographic Message Syntax (CMS):
.Bl -dash -compact -offset indent
.It
section 6.1: EnvelopedData Type
.It
section 6.2: RecipientInfo Type
.It
section 6.2.1: KeyTransRecipientInfo Type
.It
section 6.2.3: KEKRecipientInfo Type
.El
.Sh HISTORY
These functions first appeared in OpenSSL 0.9.8h,
except that
.Fn CMS_RecipientInfo_encrypt
first appeared in OpenSSL 1.0.2.
They have been available since
.Ox 6.7 .
